The absence of such frequency transformers and the inconvenience of long accelerators (so far not constructed) set researchers the task of creating energy storage means and mega-ampere current generators with an impulse power comparable to the total power of countries such as the USSR or the USA. First in Australia, then in the USA, storage-generators were constructed and used with short rail-guns i.e. with a one-turn coil, a part of which is the travelling crosspiece armature, or projectile. The first experiments were carried out with solid metal armatures, the electric current flowing through the sliding contacts between the armature and the rails (Fig. 2a). It was found that the sliding contacts limited the armature velocity to the region of 1-3 km/s. This limit led researchers to a rail-gun in which the armature is formed from the plasma arc (Fig. 2b). The Ampere force operated on the plasma armature and the latter on the rear (dielectric) wall of a projectile or a carrier that contained a projectile. Using rail accelerators with plasma armatures, impressive results in the field of massive body acceleration were achieved. A polycarbonate cube of mass 3 gm was accelerated up to a velocity of 5.5 km/s in a rail-gun of 2m length having a square cross-section of 12.7 mm on a side. Then a joint research group from Los Alamos and Livermore (USA) obtained X-ray photos of a tantalum disk accelerated by a polycarbonate carrier up to 11 km/s. Weaknesses of the Ampere Accelerator with a Plasma Armature This type of accelerator is currently the best available for obtaining high body accelerations. But it is not devoid of disadvantages, the main one being the danger of parasitic electrical discharge. As a projectile travels along the rails, the discharge circuit inductance increases and, as the electric breakdown region corresponds to maximum inductance, the possibility of parasitic electric breakdown also increases. An electric discharge behind the projectile, near the beginning of the rails, not only decreases the electric current in the plasma armature - and hence the accelerating force - but leads to destruction of the rail and the accelerator itself. Considering the very large power of full-scale acceleration systems, such a short circuit at the beginning of the rail is not acceptable - which explains the search for new electric accelerators. Anomalous Plasma Pressure In smooth plasma at complete (single) ionization, two pressures have to be taken into consideration: the kinetic pressure of electrons and ions and the magnetic pressure
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